Water-souluble, fluorescent perylenetetracarboxylic acid bisimides

ABSTRACT

The invention relates to novel perylenetetracarboxdiimide derivatives with improved performance properties.

The invention relates to novel perylenetetracarboxdiimide derivatives having improved performance properties.

Perylenetetracarboxdiimides are known for their exceptional thermal, chemical and photophysical stability (1). They are used as dyes and pigments, for example in reprographic processes (2), fluorescent solar collectors (3), photovoltaic cells (4) and dye lasers (5). Functionalized perylenetetracarboxdiimides can also be used as an initiator or reaction partner for polymerization reactions and can be incorporated into the polymers via covalent bonds (6). A further possible field of application is the use as labeling groups in detection processes, in particular in diagnostic or analytical processes on biological samples, including living cells. Many of these applications are based on the high fluorescence intensity of the perylene chromophore group and on the fact that the fluorescence excitation emission wavelengths of perylenetetracarboxdiimides lie at wavelengths of above 500 nm, at which signal disruptions caused by autofluorescence of cells, biological tissues or biological liquids are negligible.

However, one disadvantage of known perylenetetracarboxdiimides is that they have poor water solubility and/or weak fluorescence intensity in water (7). These disadvantages are brought about mainly by the aggregation of dye molecules in a hydrophilic environment, as a result of which the number of biological applications is limited (8).

DE-A-37 03 513 describes perylenetetracarboxdiimides which have one or more sulfonic acid moieties in the imide structure.

Quante et al. (Macromol. Chem. Phys. 197 (1996), 4029-4044) disclose perylenetetracarboxdiimides which contain sulfonic acid groups on the basic skeleton of the perylene chromophore. Further modified perylenetetracarboxdiimides are described in EP-A-0 648 817, EP-A-0 654 504, U.S. Pat. No. 4,378,302, EP-A-0 869 959, WO 97/22607 and by Zhubanov et al. (Zh. Org. Khim. 28 (1992), 1486-1488).

WO 02/14414 discloses functionalized perylenetetracarboxdiimides which are provided as initiators or/and as reaction partners for polymerization reactions.

These compounds exhibit increased fluorescence in aqueous solutions. However, it has not been possible to fully eliminate the disadvantages of the prior art, in particular the tendency to aggregate formation in aqueous solutions.

There is therefore a great need to provide novel perylenetetracarboxdiimides having improved properties, in particular with regard to the water solubility or/and to the fluorescence intensity in water or aqueous media.

This object is achieved in accordance with the invention by providing perylenetetracarboxdiimides having at least two charged groups on the basic skeleton of the perylene chromophore and space-filling substituents on the imide nitrogen atoms. The compounds prepared in this way exhibit fluorescence quantum yields of up to 80% in water and can optionally be modified by introduction of further functionalities, for example of hydrophilic groups or coupling groups, into the imide structure.

The invention thus provides perylenetetracarboxdiimides of the structural formula (I)

in which R¹ and R² are each independently an organic moiety which is bonded via a secondary or tertiary carbon atom to the imide nitrogen atom, and at least two of R³, R⁴, R⁵ and R⁶ are each independently organic moieties which contain at least one positively or/and negatively charged group.

The R¹ and R² moieties present as part of the imide structure are secondary or tertiary aliphatic moieties or cyclic moieties having typically 3-30 carbon atoms, in particular mono- or bicyclic aromatic or heteroaromatic moieties, for instance phenyl, pyridyl or naphthyl, which optionally bear one or more substituents. Examples of suitable substituents for aliphatic or saturated cyclic moieties are CN, NO₂, halogen (e.g. F, Cl, Br or I), OH, OR⁷, OCOR⁷, SH, SR⁷, SCOR⁷, SO₂R⁷, CHO, COR⁷, COOH, COOM, COOR⁷, CONH₂, CONHR⁷, CON(R⁷)₂, SO₃H, SO₃M, SO₃R⁷, NH₂, NHR⁷ or N (R⁷)₂, wherein M is a cation, e.g. an alkali metal ion such as sodium, potassium, etc., and R⁷ is an optionally halogen-substituted C₁-C₆-alkyl moiety. Cyclic moieties, for example aromatic or heteroaromatic moieties, may additionally be substituted by one or more R⁷ moieties. In addition, reactive functionalities may be introduced into the R¹ or/and R² moieties in order to enable coupling to biological substances. Examples of such reactive functionalities are active esters, maleimides, isocyanates, sulfonyl halides, carboxylic acid halides, in particular carboxylic acid chlorides, iodoacetamides, aziridines, epoxides, acyl azides and acyl nitriles.

At least two of the R³, R⁴, R⁵ and R⁶ moieties bear at least one charged group. Preferably all four R³, R⁴, R⁵ and R⁶ moieties bear at least one charged group. The charged group is preferably a charged group which is charged in neutral media, for example at pH 7, for example a positively charged group, for instance an amino group or an ammonium group, in particular a quaternized ammonium group, or an alkylated heteroaromatic nitrogen atom, in particular an N-alkylpyridinium, N-alkylquinolinium or N-alkylisoquinolinium group, wherein the alkyl moiety preferably has up to 6 carbon atoms and may optionally be substituted as described above. Examples of suitable negatively charged groups are sulfonic acid or carboxylic acid groups, SO₃H and COOH, and also their SO₃M and COOM salts, where M is a cation, for example an alkali metal ion, for instance potassium or sodium. In addition, R³, R⁴, R⁵ or/and R⁶ may also contain a plurality of identically or oppositely charged groups, amphiphilic groups being formed in the latter case. Particularly preferred amphiphilic groups are heteroaromatic nitrogen atoms which are alkylated by a moiety which bears a —CO₂H, —SO₃H, —CO₂M or —SO₃M group.

It is also preferred that at least two of the R³, R⁴, R⁵ and R⁶ moieties comprise aromatic or heteroaromatic moieties, in particular monocyclic or bicyclic moieties, for instance phenyl or pyridine.

In a particularly preferred embodiment, at least two of R³, R⁴, R⁵ and R⁶ are represented by the general structural formula (II) —O—Ar  (II) in which Ar is an aromatic or heteroaromatic moiety which contains at least one charged group as specified above. In the case that perylenetetracarboxdiimides having negative charge carriers are used, at least one of R³, R⁴, R⁵ and R⁶ may have the general structural formula (III):

in which M is a cation and n is 1, 2 or 3.

In the case of the use of perylenetetracarboxdiimides having positive charge carriers, at least one of R³, R⁴, R⁵ and R⁶ may have the general structural formula (IV):

in which R⁷ is an optionally substituted C₁-C₆-alkyl moiety, preferably C₁-C₄-alkyl moiety, and Y is an anion, e.g. a halide ion. When the R⁷ moiety bears a negatively charged group as a substituent, an amphiphilic moiety is obtained.

The inventive perylenetetracarboxdiimides are typically prepared from an industrially readily obtainable di- or tetrahalo-substituted perylenetetracarboxdianhydride by condensation with a primary amine, e.g. H₂NR¹ or H₂NR². The resulting halogen-substituted perylenedi- or -tetracarboxdiimides of the general structural formula (V)

in which R¹ and R² are as defined above and at least two of X¹, X², X³ and X⁴ are each halogen, in particular Cl or Br, are subsequently reacted with a compound of the general structural formula (VI) HO—Ar′  (VI) in which Ar′ is an aromatic or heteroaromatic moiety. This reaction forms tetra-substituted perylenetetracarboxdiimides of the general structural formula (VIIa) or disubstituted perylenetetracarboxdiimides of the general structural formula (VIIb):

Subsequently, hydrophilic groups, as specified above, may be introduced into the aromatic or heteroaromatic Ar′ moieties. For example, at least one SO₃H or SO₃M group may be introduced into Ar′ by reaction with H₂SO₄ under suitable conditions. Alternatively, heteroaromatic nitrogen atoms in Ar′ may be alkylated, for example by reaction with an alkyl halide, e.g. CH₃I, under suitable conditions.

The inventive compounds may be employed in all technical fields suitable for the use of perylenetetracarboxdiimides, for example in dye lasers, as labeling groups in analytical processes, as tracers, in scintillation counters, in fluorescence solar collectors, in liquid crystals, in cold light sources, in materials testing, as photoconductors, in photographic processes, in illumination and display elements, as semiconductors, etc.

The dyes are preferably used in conjunction with a suitable carrier, for example in a concentration of from 0.0005 to 0.5% based on the weight of the carrier. The dyes or conjugates of the dyes, for example covalent conjugates with biomolecules such as nucleic acids, proteins, peptides, saccharides, etc., may be dissolved in liquids, for example organic or/and aqueous solvents, or in solids, for example polymers.

The present invention will be further illustrated by diagrams and examples.

FIG. 1 shows a reaction scheme for the preparation of the tetrasubstituted compounds specified in examples 1-4.

FIG. 2 shows the disubstituted compounds specified in example 5.

EXAMPLES Example 1 Preparation of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(phenoxy)perylene-3,4:9,10-tetracarboxdiimide

5 g (5.9 mmol) of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetrachloroperylene-3,4:9,10-tetracarboxdiimide, 2.7 g (29 mmol) of phenol and 4 g (29 mmol) of K₂CO₃ were suspended under an inert gas atmosphere in 200 ml of N-methylpyrrolidone (NMP). The reaction mixture was heated to 110° C. and stirred for 6 h. After cooling to room temperature, the mixture was poured into 500 ml of an aqueous 2M hydrochloric acid solution. The resulting precipitate was filtered, washed with water to neutrality of the filtrate and dried at 75° C. under reduced pressure. The product was purified further by column chromatography (SiO₂/CH₂Cl₂).

Yield 4.9 g (77%) of red solid

M.P.>300° C.; ¹H NMR (300 MHz, C₂D₂Cl₄, 300 K): δ=8.13 (s, 4 H), 7:33 (t, ³J=7.5 Hz, 2 H), 7.24-7.08 (m, 12 H), 7.02 (t, ³J=7.5 Hz, 4 H), 6.93 (d, ³J=7.5 Hz, 8 H), 2.60 (sept, ³J=6.9 Hz, 4 H), 1.03 (d, ³J=6.9 Hz, 24 H); ¹³C NMR (75 MHz, C₂D₂Cl₄, 300 K): δ=163.50, 156.17, 155.39, 145.68, 133.41, 130.70, 130.31, 129.63, 125.07, 124.22, 122.90, 121.02, 120.48, 120.20, 29.30, 24.42; IR (KBr): ν=3066, 2962, 2868, 2362, 1707, 1675, 1586, 1508, 1487, 1408, 1342, 1311, 1285, 1199, 1074, 1021, 959, 904, 875, 811, 749, 689, 578, 522 cm⁻¹; UV-Vis (CHCl₃): λ_(max) (ε)=542 (31 000), 578 nm (48 500 M⁻¹ cm⁻¹); fluorescence (CHCl₃, excitation=542 nm): λ_(max)=613 nm, MS (FD, 8 kV) : m/z=1080.2 (100%) [M⁺]

Example 2 Preparation of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-sulfonylphenoxy)-perylene-3,4:9,10-tetracarboxdiimide

2 g (1.9 mmol) of the compound prepared in example 1 were dissolved in 4 ml of concentrated sulfuric acid and stirred at room temperature (20° C.). for 12 h. The product was precipitated by addition of water, filtered and dried at 75° C. under reduced pressure.

M.P.>300° C.; ¹H NMR (300 MHz, CH₃OH-D₄, 300 K): δ=7.91 (s, 4 H), 7.59 (d, ³J=8.8 Hz, 8 H), 7.17 (t, ³J=7.6 Hz, 2 H), 6.88 (d, ³J=8.8 Hz, 8 H), 2.45 (sept, ³J=Hz, 4 H), 0.85 (d, ³J=Hz, 24 H); ¹³C NMR (75 MHz, CH₃OH-D₄, 300 K): δ=164.61, 158.49, 156.94, 147.21, 142.46, 131.83, 129.49, 125.01, 124.43, 122.35, 121.86, 120.75, 30.29, 24.25, 13.40; IR (KBr): ν=2970, 2361, 1701, 1655, 1588, 1491, 1410, 1340, 1287, 1208, 1180, 1125, 1066, 1032, 1007, 882, 846, 699, 580 cm⁻¹; UV-Vis (H₂O): λ_(max) (ε)=536 (20 100), 571 nm (27 800 M⁻¹ cm⁻¹); MS (LD-TOF): m/z=1401.1 [M⁺]

Example 3 Preparation of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(3-pyridoxy)perylene-3,4:9,10-tetracarboxdiimide

5 g (5.9 mmol) of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetrachloroperylene-3,4:9,10-tetracarboxdiimide, 2.85 g (30 mmol) of hydroxypyridine and 4 g (30 mmol) of K₂CO₃ were dissolved in 250 ml of NMP. The reaction mixture was stirred at 110° C. under an inert gas atmosphere. After 4 h, the mixture was cooled to room temperature and neutralized with dilute hydrochloric acid. The crude product was filtered, washed with water and dried at 75° C. under reduced pressure. The resulting solid was further purified by column chromatography with ethyl acetate.

M.P.>300° C.; ¹H NMR (250 MHz, C₂D₂Cl₄, 300 K): δ=8.29 (d, ³J=6.3 Hz, 4 H), 8.28 (s, 4 H), 8.14 (s, 4 H), 7.35 (t, ³J=7.9 Hz, 2 H), 7.30-7.27 (m, 4 H), 7.19 (d, ³J=7.9 Hz, 4 H), 7.17 (d, ³J=8.2 Hz, 4 H), 2.58 (sept, ³J=6.6 Hz, 4 H), 1.03 (d, ³J=6.6 Hz, 24 H); ¹³C NMR (75 MHz, C₂D₂Cl₄, 300 K); δ=162.99, 155.52, 152.09, 146.32, 145.65, 141.97, 133.50, 130.29, 129.84, 127.30, 124.93, 124.33, 123.68, 121.38, 121.15, 120.49, 94.29, 29.35, 24.45, 16.32, 14.85; IR (KBr): ν=3061, 2963, 2868, 2361, 1707, 1671, 1593, 1508, 1474, 1423, 1407, 1339, 1309, 1279, 1209, 1102, 1019, 958, 875, 808, 738, 705, 581 cm⁻¹; UV-Vis (CH₃OH): λ_(max) (ε)=526 (30 500), 560 nm (48 800 M⁻¹ cm⁻¹ ); fluorescence (CH₃OH, excitation: 526 nm): λ_(max)=610 nm; MS (FD, 8 kV): m/z (rel. int.)=1083.2 (100%) [M⁺]

Example 4 Preparation of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra[3-(N-methylpyridinium)oxy]perylene-3,4:9,10-tetracarboxdiimide

1 g (0.92 mmol) of the compound prepared in example 3 was dissolved in 100 ml of methanol at 80° C. 655 mg (4.6 mmol) of methyl iodide were added to the stirred solution and the mixture was kept under reflux for 12 h. The resulting product fell in high purity.

M.P.>300° C.; ¹H NMR (250 MHz, CH₃OH-D₄, 300 K) : δ=9.22-9.01 (m, 2 H), 8.78-8.42 (m, 12 H), 8.12-7.97 (m, 2 H) , 7.88-7.68 (m, 2H), 7.57-7.33 (m, 8 H) , 4.47-4.40 (s, 12 H), 2.91-2.69 (m, 4 H), 1.15-1.11 (m, 24 H); ¹³C NMR (75 MHz, CH₃OH-D₄, 300 K): δ=164.40, 164.26, 157.23, 157.05, 154.26, 153.88, 147.18, 146.61, 142.63, 138.61, 135.80, 131.58, 130.79, 130.06, 129.30, 126.65, 126.44, 125.13, 124.56, 121.62, 67.38, 30.30, 24.36, 13.42; IR (KBr): ν=2963, 2361, 2336, 1704, 1665, 1594, 1503, 1473, 1408, 1337, 1309, 1275, 1212, 812, 672 cm⁻¹; UV-Vis (H₂O): λ_(max) (ε)=520 (19 300), 555 nm (25 700 M⁻¹ cm⁻¹); fluorescence (H₂O, excitation: 520 nm): λ_(max)=601 nm

Example 5 Preparation of Disubstituted Perylenetetracarboxdiimides

Starting from N,N′-bis(2,6-diisopropylphenyl)-1,7-dibromoperylene-3,4:9,10-tetracarboxdiimide, N,N′-bis(2,6-diisopropylphenyl)-1,7-di(4-sulfonylphenoxy)-perylene-3,4:9,10-tetracarboxdiimide was prepared according to the reaction sequence described in examples 1 and 2, and N,N′-bis(2,6-diisopropylphenyl)-1,7-di[3-(N-methylpyridinium)oxy]perylene-3,4:9,10-tetracarboxdiimide was prepared according to the reaction sequence described in examples 3 and 4.

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1. A perylenetetracarboxylic acid bisimide of the structural formula (I)

in which R¹ and R² are each independently an organic moiety which is bonded via a secondary or tertiary carbon atom to the imide nitrogen atom, and at least two of R³, R⁴, R⁵ and R⁶ are each independently organic moieties which contain at least one positively or/and negatively charged group.
 2. A compound as claimed in claim 1, characterized in that R¹ or/and R² are secondary or tertiary aliphatic moieties or cyclic moieties.
 3. A compound as claimed in claim 1, characterized in that R¹ or/and R² are aromatic or heteroaromatic moieties, in particular phenyl, pyridyl or naphthyl moieties, which optionally contain one or more substituents.
 4. A compound as claimed in claim 1, characterized in that at least R³, R⁴, R⁵ and R⁶ are each independently an organic moiety which bears (in neutral media) a positively charged group.
 5. A compound as claimed in claim 1, characterized in that R³, R⁴, R⁵ and R⁶ are each independently an organic moiety which bears a group selected from quaternary ammonium and N-alkylated heteroaromatic N-groups such as N-alkylpyridinium, N-alkylquinolinium or N-alkylisoquinolinium groups.
 6. A compound as claimed in claim 1, characterized in that R³, R⁴, R⁵ and R⁶ are each independently an organic moiety which bears (in neutral media) a negatively charged group.
 7. A compound as claimed in claim 1, characterized in that at least two of R³, R⁴, R⁵ and R⁶ are each independently an organic moiety which bears a group selected from SO₃H, COOH, SO₃M and COOM, wherein M is a cation.
 8. A compound as claimed in claim 1, characterized in that R³, R⁴, R⁵ or/and R⁶ comprise aromatic or heteroaromatic moieties, in particular phenyl or pyridine moieties.
 9. A compound as claimed in claim 1, characterized in that at least one of R³, R⁴, R⁵ and R⁶ has the general structural formula (II): —O—Ar  (II) in which Ar is an aromatic or heteroaromatic moiety which contains at least one charged group.
 10. A compound as claimed in claim 9, characterized in that at least one of R³, R⁴, R⁵ and R⁶ has the general structural formula (III):

wherein M is a cation and n is an integer of 1-3.
 11. A compound as claimed in claim 9, characterized in that at least one of R³, R⁴, R⁵ and R⁶ has the general structural formula (IV):

wherein R⁷ is an optionally substituted C₁-C₆-alkyl moiety and Y is an anion.
 12. A process for preparing perylenetetracarboxdiimides of the general structural formula (I), comprising the steps of: (a) reacting halogen-substituted perylenedi- or perylenetetracarboxdiimides of the general structural formula (V):

in which R¹ and R² are each as defined in claim 1 and at least two of X¹, X², X³ and X⁴ are each halogen, in particular Cl or Br, with a compound of the general structural formula (VI): HO—Ar′  (VI) in which Ar′ is an aromatic or heteroaromatic moiety to give tetrasubstituted perylenetetra-carboxdiimides of the general structural formula (VIIa) or to give disubstituted perylenetetra-carboxdiimides of the general structural formula (VIIb):

and (b) introducing hydrophilic groups into the aromatic or heteroaromatic Ar′ moieties.
 13. The process as claimed in claim 12, characterized in that step (b) comprises the introduction of at least one SO₃H or SO₃M group into Ar′, wherein M is a cation.
 14. The process as claimed in claim 12, characterized in that step (b) includes the alkylation of at least one heteroaromatic nitrogen atom in Ar′. 